Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
cac duc » cac du, cao duc, cac dac
va chua » vua chua, ca chua, va chu
duc ban » duc tan, duc van, dua ban
te sach » toc sach
ky dang » ky nang, ky danh
ky tang » ky nang, kho tang, ky trong
van cac » van hac, van cau, van bac
va cua » via cua, ca cua, ma cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((ky tang) or (ky dang)) xa hoi. hieu van cac duc ban thanh ((va cua) OR (va chua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ky tang) OR (ky dang)) xa hoi. hieu van cac duc ban thanh ((va cua) OR (va chua)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ky tang) or (ky dang)) xa hoi. hieu van cac duc ban thanh ((va cua) OR (va chua)) triet".
• Adding a wildcard symbol may retrieve word variants: te sach ((ky tang) or (ky dang)) xa hoi. hieu van cac duc ban thanh ((va cua) OR (va chua)) triet*.